[Qemu-devel] Re: [PATCH v5 0/4] piix_pci: optimize irq data path

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Mar 23, 2011 at 11:17:19AM +0900, Isaku Yamahata wrote:
> v4 has minor typo. I sent it too early. Here's fixed one.
> 
> v3 -> v4 Main changes are
> - use pirq, pci_intx instead of irq_num in piix_pci.c
> - patch 4/4 cleans the code a bit

With this applied e1000 fails to work for me.
Command line:

qemu-system-x86_64 -enable-kvm -m 1G -drive
if=virtio,file=/home/mst/rhel6.qcow2  -netdev user,id=bar -net
nic,netdev=bar,model=e1000,macaddr=52:54:00:12:34:57  -redir
tcp:8022::22 -net nic,model=e1000,netdev=foo,macaddr=52:54:00:12:34:56
-netdev
tap,id=foo,ifname=msttap0,script=/home/mst/ifup,downscript=no
-nographic

Could you try that please?

> 4/4 needs more extensive tests. So please feel free to pick it up now or
> drop it for now.
> 
> patch description:
> This patch series optimizes irq data path of piix_pci.
> So far piix3 tracks each pirq level and checks whether a given pic pins is
> asserted by seeing if each pirq is mapped into the pic pin.
> This is independent on irq routing, but data path is on slow path.
> 
> Given that irq routing is rarely changed and asserting pic pins is on
> data path, the path that asserts pic pins should be optimized and
> chainging irq routing should be on slow path.
> The new behavior with this patch series is to use bitmap which is addressed
> by pirq and pic pins with a given irq routing.
> When pirq is asserted, the bitmap is set and see if the pic pins is
> asserted by checking the bitmaps.
> When irq routing is changed, rebuild the bitmap and re-assert pic pins.
> 
> Changes v4 -> v5:
> - typo
> 
> Changes v3 -> v4:
> - use pirq, pci_intx instead of irq_num in piix_pci.c
> - use symbolic constant PIC_NUM_PINS 
> - introduced new patch 4/4 which cleans up a bit.
> 
> Changes v2 -> v3:
> - s/dummy_for_save_load_compat/pci_irq_levels_vmstate/g
> - move down unused member of pci_irq_levels_vmstate in the structure
>   for cache efficiency
> 
> Changes v1 -> v2:
> - addressed review comments.
> 
> Isaku Yamahata (4):
>   pci: add accessor function to get irq levels
>   piix_pci: eliminate PIIX3State::pci_irq_levels
>   piix_pci: optimize set irq path
>   piix_pci: load path clean up
> 
>  hw/pci.c      |    7 +++
>  hw/pci.h      |    1 +
>  hw/piix_pci.c |  128 +++++++++++++++++++++++++++++++++++++++++++++-----------
>  3 files changed, 111 insertions(+), 25 deletions(-)